Control device for circuit breakers



July 26,1938. s. T. scHoFlELD 2,125,130

CONTROL DEVICE FOR CIRCUIT BRAKERS Filed Dec. 31, 1936 Patented July 26, 1938 I UNITED STATES PATENT OFFICE l z,1z5,1so

coN'raoL pEvrcE Eon cmom'r naEAxEas Stanley T. Schofield, deceased, late of Wilkinsburg, Pa., by Martha M. Schoiield, administratrix, Wilkinsburg, Pa., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application December 31, 1936, Serial No. 118,577

18 Claims. (Cl. 20o-106) The invention relates to electric control devices in general and more particularly to electric control devices for tripping circuit breakers to open the contacts thereof.

It will be understood that the trip device embodying the features of the invention is capable of application to substantially any type of circuit breaker and for this reason the circuit breaker mined amplitude of vibration.

In medium and high voltage alternating-curwith which the trip device is shown associated in 5 rent power distribution systems, the circuit the drawlng'has been illustrated in a diagrambreakers used are relatively large and considermatic manner. able energy is required to r'n'ove the relatively AReferring to the drawing, the circuit breaker, heavy latch means to trip the breakers. In which is illustrated diagrammatically, comprises many instances, auxiliary sources of power are a pair of stationary contacts 3, a movable brush l0 not available or practical and the practice has Contact 5 connected to a pair of toggle links 1 and been` to derive the energy for tripping the breaker 9 which form a part of the operating mechanism from a current transformer associated with the for closing the-circuit breaker, a releasable latch circuit or line controlled by the breaker. One means il for restraining the movable brush contype of arrangement has been the provision of tact 5 in closed circuit position, and a spring l5 an alternating-current electromagnet for tripmeans I3 for biasing the movable brush contact ping the latches of the breaker, the electromag- 5 to the open circuit position. The latch memnet being connected in a control circuit which ber H is pivotally mounted by means of a pivot is energized by a current transformer coupled Din l5 andiS biased tOlatehing DOStiOn, eS ShOWn,

to the line controlled by the breaker. The inby means of a weighted extension I1. 20 eiiicient useby the electromagnet of the limited The trip device comprises in general a suppower available makes this arrangement un- Dort I9, a trip lever 2l, a latch 23, a vibratory satisfactory particularly in view of the use of energy storing device indicated generally at 25, larger and heavier circuit breakers. an electromagnet 21 for the vibrating device to 25 It is accordingly an object of the invention to store energy therein, and a control circuit 29 for 25 provide a novel trip device for tripping large energizing the eleetl`0megnet circuit breakers, which device is operable by a The trip lever 2| is pivotally mounted on a low energy control circuit. bracket 3| by means of a pivot pin 33. One end Another Object; 0f the invention is the provi- 0f the trip level' 2| Carries a trip projection which,

sion of an improved trip device for circuit breakin the fOlm ShOWn, COmDriSeS a Screw 35 which 30 ers capable of tripping larger breakers with a, is threaded through the trip lever adjacent its lower energy control circuit than any trip devices left-hand end- A 100k 1111i? 37 iS DrOVided for heretofore known or used, y locking the screw in adjusted position. The

Another object of the invention is to provide Opposite end 0f the trip lever Carries the DiVOted 35 a novel low energy alternating-current trip device latch member 23- The latch member 23 has a 35 for a circuit breaker which is simple, reliable, depending hOOk-Shaped latch DOftOIl 39 and a and inexpensive to manufacture. weighted extension 4|. The latch member 23 is Another object of the invention is the provipiVOlJellY mounted 0n the right-hand end 0f the sion of a novel low energy alternating-current trip lever by means of a pivot pin 43 and is biased 4o trip device for a circuit breaker, which embodies in a clockwise direction about the pivot pin 43 40 an adjustable means for varying the time reby means of the weighted extension 4l. A stop quired for tripping the breaker. pin 45 is mounted on the trip lever 2| for limiting 'I'he novel features that areconsidered charclockwise rotation of the latch member 23. acteristic of the invention are set forth in par- The vibratory energy storing device comprises 45 ticular in the appended claims. The invention a spring 4l and a weight member 49. One end 45 itself, however, both as to structure and operaof the spring 41 is bent over and secured t the tion, together with additional objects and advansupport I9 by means of a holding screw 5|. The tages thereof, will best be understood from the weight member 49 is secured to the opposite or following detailed description oi an embodiment free end of the spring 4l in any suitable manner.

50 of the invention when read in connection with the The upper end of the weight member 49 is pro- 50 accompanying drawing, in which: vided with a latch engaging projection 53 which The single, partly diagrammatic, figure shows is adapted to be latched into engagement with the trip device embodying the features of inthe hook-shaped end 39 of the latch member 23 vention, .in side elevation; the circuit breaker when the weight member attains a predeter- 55 being shown in diagrammatic form. 55

The alternating-current electromagnet 21 is mounted adjacent the central portion of the spring 41 by means of an angle-shaped bracket 55. The vertical leg of the bracket is provided with an adjusting slot 51, and is secured to the support I9 by means of a bolt 59 and a nut 6I. The body portion of the bolt. 59 passes through an opening in the support I5, through the slot 51 of the bracket 55, and a lock washer 63 is positioned between the vertical leg of the bracket 55 and the nut 6I. This arrangement provides an adjustable mounting means for the electromagnet 21, whereby the air gap between the core of the electromagnet and the spring 41 may be adjusted in order to vary the time required for the weight member to attain a predetermined amplitude of vibration. The electromagnet 21 is connected in a control circuit 29 which, in the embodiment shown, receives its energy from a. current transformer 65 which is coupled to the line LI controlled by the breaker. A control switch 61 is interposed in the circuit 29 for controlling energization of the electromagnet 21.

The spring 41 is composed of magnetic material so as to be influenced by the pull of the electromagnet. If desired, the spring 41 may be provided with an armature 69 secured to the spring at a point above the core of the electromagnet 21. The spring 41 and the weight member 49 are so proportioned that the natural or inherent frequency of vibration of these connected members corresponds to-the frequency of the alternating pull of the electromagnet 21 or to the frequency of the control circuit 29 so that when the control circuit is closed by the switch G1, the electromagnet causes the spring 41 and the connected weight member 49 to vibrate with increasing amplitude to store energy in said Weight.

The operation of the device is as follows: With the parts in the position shown in the drawing, let it be assumed that it is Idesired to trip the breaker. Control switch 61 is closed either manually or by means of a relay to effect energization of the electromagnet 21 by means of the control circuit 29. The energization of the electromagnet 21 causes the spring 41j'and connected weight member 49 to vibrate with increasing amplitude. After a predetermined time, the amplitude of vibration of the spring 41 and connected weight member 49 is increased to such an extent that the upper end of the weight member 49 engages the weighted extension 4I of the latch 23 to effect partial counter-clockwise rotation of the latch. The partial counter-clockwise rotation of the latch 23 causes the hook-shaped latch portion 39 to engage under the latch projection 53 of the weight member 49. The downward movement of the weight member, in which considerable energy has been stored, eii'ects clockwise rotation of the trip lever 2l about its pivot pin 33 and causes the screw 35 to engage and move latch means II in a clockwise direction to effect release of the toggle linkage 1-9. The release of the toggle linkage 1-9 permits the biasing spring means I3 to move the toggle links to collapsed position which eiects movement of the movable brush contact 5 to its open circuit position.

At a predetermined point in the downward movement of the weight member 49, the latch 23 releases the trip lever 2| from its connection with the weight member 49. The trip lever 2l is returned to the normal position shown by the return movement of the biased latch means II to its latching position. The control circuit 29 is deenergized by the opening of the movable contact 5. The parts of the trip device are thus restored to their normal position ready for a subsequent operation. The circuit breaker is closed by the operating mechanism (not shown), and the latch means I I reengages the toggle linkage 1-9 to latch the breaker in closed circuit position.

It will thus be seen that even though the power available in the control circuit 29 is low, the improved trip device provides an arrangement for tripping extremely heavy breakers by the energy derived from the low power control circuit. This is rendered possible by reason of the fact that the energy derived from the control circuit is stored in the vibratory device comprising the spring 41 and the weight member 49, over a. period of time. Thus enough energy can be stored in the weight member 49 to trip large heavy breakers.

'I'he trip device described may also be utilized as a time delay overload trip device by providing a means for closing the switch 61 in response to overload conditions in any well known manner. In such case, the time delay between the energization of the control circuit 29 and the tripping of. the breaker can be varied by adjusting the position of the electromagnet 21 by means of the slot 51, the bolt 59, and the nut 6 I; to vary the air gap between the core of the electromagnet and the spring 41. By increasing the air gap, the. weight member 49 will be influenced less by the electromagnet and thus require a longer time to build up to the required amplitude of vibration to trip the breaker.

The trip device may also be used as an overvoltage or under-voltage trip means by making the control switch 61 responsive to over-voltage or under-voltage conditions.

It is obvious that the trip device described is applicable to various types of circuit breakers. For example, in the case of a three-pole circuit breaker, the trip lever ZI would be arranged to engage and move the trip bar of the breaker to tripping position when the weight member 49 attains a predeterminedY amplitude of vibration. Likewise, the trip device is applicable to other forms of circuit breakers involving di'erent types of latch means and operating mechanisms.

It will thus be seen that the invention provides a novel and improved trip device for circuit breakers which is simpler, more reliable, and less expensive to manufacture than trip devices that have heretofore been known or used. The invention also provides an alternating-current trip device for circuit breakers which is capable of tripping larger breakers with a lower energy control circuit than has heretofore been considered possible.

While the invention has been disclosed in accordance with the provisions of the patent statutes, it is to be understood that various changes in details of structure may be made without departing from the spirit of the invention. It is desired, therefore, that the invention be limited only by the reasonable construction of the appended claims, and by the prior art.

The invention claimed is as follows:

1. In a circuit breaker having relatively movable contacts biased to open circuit position and means for releasably holding said contacts in closed circuit position, the combination of a trip device comprising a vibratory mass, electromagnetic means for vibrating said mass with increasring amplitude, said mass'being operable upon the attainment of a predetermined amplitude of vibration to ei'fect release oi' said holding means to permit opening of said contacts.

2. In a control device, the combination of a vibratory member, an electromagnetic means for vibrating said member with increasing amplitude and means operated by said member when it attains a predetermined amplitude of vibration for eiecting actuation of said control device.

'3. In a circuit breaker having relatively movable contacts, means biasing said contacts to open circuit position, releasable latch means for holding said contacts closed, a trip device comprising a vibratory member, an electromagnetic means for vibrating said member with increasing amplitude, said member being operable upon the attainment ot a predetermined amplitude of vibration to release said latch means to allow said contacts to be opened by said biasing means.

'4. In a control device, a vibratory mass, an alternating-current electromagnet for vibrating said mass, a low energy alternating-current control circuit for said electromagnet, the energization of said circuit causing said electromagnet to vibrate said mass with increasing amplitude, said mass being operable upon the attainment of a predetermined amplitude of vibration to effect operation of said device.

5. In a circuit breaker having relatively movable contacts biased to open circuit position, releasable means for holding said contacts closed,

an energy storing device, means including anV electromagnet and a low energy control circuit for storing energy in said device at a certain rate, said device being operable upon the attainment of a predetermined amount of energy to eiIect release of said holding means to permit said contacts to open.

6. In a circuit controlling device, the combination of a spring suspended vibratory mass, an alternating-current electromagnet, a low energy alternating control circuit for energizing said electromagnet, said spring suspended mass having a natural frequency of vibration corresponding to the frequency of the alternating pull of said electromagnet so that said spring suspended mass is vibrated with increasing amplitude by said electromagnet, and means operable by said mass when it attains a predetermined amplitude of vibration for effecting operation of said device.

'7. In a circuit breaker, relatively movable contacts, means biasing said contacts to open circuit position, releasable means for holding said contacts closed, a trip device comprising an energy storing vibratory member, an alternatingcurrent electromagnet for vibrating said member to store energy therein, a low energy control circuit for energizing said electromagnet, the natural frequency of vibration of said member corresponding to the alternating pull of said electromagnet so that said member is vibrated with increasing amplitude as energy is stored therein, means operable by said member when a predetermined amount of energy is stored therein'to relase said holding means to permit said contacts to open.

8. In combination, a circuit'controlling device, a spring secured to a support at one end, a Weight secured to the free end of said spring, an altermating-current electromagnet mounted adjacent said spring for vibrating the same when said electromagnet is energized, a low energy altertion oi' said spring and connected weight corresponding to the frequency of the control'circuit so that said spring and weight are vibrated with increasing amplitude during energization of said circuit, means operable by said weight when said spring and weight attain a predetermined amplitude of vibration fo; eiecting actuation of said circuit lcontrolling device.

9. In a circuit breaker, relatively movable contacts biased to open circuit position, a releasable latch means'for holding said contacts closed, a trip devicecomprising a vibratory member, an alternating-current electromagnet for vibrating said member, a low energy control circuit for energizing said electromagnet, the proportions of said member being such that its natural frequency of vibration corresponds to the frequency of pull of said electromagnet so that the amplitude of vibration of said member increases at a certain rate, means operable by said member when it attains a predetermined amplitude of vibration for moving said latch means to cause said contacts to open.

l0. A circuit controlling device, control means for said device comprising a vibratory member, an alternating-current electromagnet for vibrating said member, a low energy control circuit -for energizing said electromagnet, the proportions of said member being such that its natural frequency of vibration corresponds to the frequency of pull of said electromagnet so that the amplitude of vibration of said member increases at a certain rate, means operable by said member when it attains a predetermined amplitude of vibration for effecting operation of said device, and means for varying the rate of increase of amplitude of vibration of said member to vary the time required for said member to eifect operation of said device.

11. In a control device, means for actuating said device comprising a vibratory member, an alternating-current electromagnet for vibrating said member, a low energy control circuit for energizing said electromagnet, said electromagnet When energized causing said member to vibrate with increasing amplitude, said member when it attains a predetermined amplitude of vibration effecting actuation of said device, and means for varying the time required for said member to attain said predetermined amplitude.

12. In a circuit breaker, stationary Contact means, a switch vmember movable to open or to closed circuit position to open or to close the circuit, means biasing said switch member to open circuit position, releasable latch means for holding said switch member in closed circuit position, a trip device for releasing said latch means comprising a vibratory spring supported weight means,said Weight means being operable upon the attainment of a predetermined amplitude of Vibration to release said latch means to allow said switch member to move to open circuit position, an alternating-current electromagnet for vibrating said weight means to store energy therein, and a low energy alternating-current control circuit for energizing said electromagnet, the natural frequency of vibration of said spring supported weight means corresponding to the frequency of said control circuit so that said Weight means is vibrated with increasing amplitude during energization of said circuit.

13. In a circuit breaker, stationary contact means, a switch member movable to open or to closed circuit position to open or to close the circuit, means biasing said switch member to open circuit position, releasable latch means for holding said switch member in closed circuit position,

cuit so that said weight means is vibrated with increasing amplitude during energization of said circuit, and means for varying the time required for said weight means to attain said predetermined amplitude.

14. In a circuit controlling device, means for vactuating said device, comprising a vibratory spring supported weight means, said Weight means being operable upon the attainment of a predetermined amplitude of vibration to effect actuation of said device, an alternating-current electromagnet for vibrating said weight means, a low energy alternating-current control circuit for energizing said electromagnet, the natural frequency of vibration of said spring supported weight means corresponding to the frequency of said control circuit so that said Weight means is vibrated with increasing amplitude during energization of said circuit, and means for adjusting the position of said electromagnet to vary the time required for said weight means to attain said predetermined amplitude.

15. In a circuit breaker, relatively mova ble contacts, means biasing said contacts to open circuit position, releasable latch means for holding said contacts closed, a trip device comprising a spring secured to a support at one end, a Weight secured to the free end of said spring, an alterhating-current electromagnet mounted adjacent said spring for vibrating the same when said electromagnet is energized, a low energy alternatingcurrent control circuit for energizing said electromagnet, the natural frequency of vibration of said spring and connected weight corresponding to the frequency of the control circuit so that said spring and weight are vibrated with increasing amplitude during energization of said circuit, means operable by said Weight when said spring and weight attain a predetermined amplitude of vibration for effecting release of said latch means to allow said biasing means to open said contacts, and means for varying the time required for said spring and weight to attain said predetermined amplitude of vibration:

16. In a circuit controlling device, means for actuating said device comprising a spring secured to a support at one end, a Weight secured to the free end of said spring, an alternating-current electromagnet mounted adjacent said spring for vibrating the same when said electromagnet is energized, a low energy alternating-current control circuit for energizing said electromagnet, the natural frequency of vibration of said spring and connected weight corresponding to the frequency of the control circuit so that said spring and Weight are vibrated with increasing amplitude during energization of said circuit, said weight \and spring upon the attainment of a predetermined amplitude of vibration effecting actuation of said device, and means for adjusting the position of said electromagnet relative to said spring for varying the time required for said spring and Weight to attain said predetermined amplitude of vibration.

17. In a circuit breaker, relatively movable contacts, means biasing said contacts to open circuit position, releasable means for holding said contacts closed, a trip device comprising an energy storing vibratory member, an alternatingcurrent electromagnet for vibrating said member to store energy therein, a low energy control circuit for energizing said electromagnet, the natural frequency of vibration of said member corresponding to the alternating pull of said electromagnet so that said member is vibrated with increasing amplitude as energy is stored therein, means operable by said member when a predetermined amount of energy is stored therein to release said holding means to permit said contacts to open, and means for varying the time required for said vibratory member to eiect release of said holding means.

18. In a circuit breaker having relatively movable contacts biased to open circuit position, releasable means for holding said contacts. closed, an energy storing device, means including an electromagnet and a low energy control circuit for storing energy in said device at a certain rate, said device being operable upon the attainment of a predetermined amount of energy to effect release of said holding means to permit said contacts to open, and means for varying the time interval between energization of said circuit and the release of said holding means.

MAR'IHA M. SCHOFIELD, Administratrz'x of the Estate of Stanley T. Schofield, lDeceased. 

